21st Conf. on Severe Local Storms and 19th Conf. on Weather Analysis and Forecasting/15th Conf. on Numerical Weather Prediction

Wednesday, 14 August 2002: 2:15 PM
Kinematic and microphysical evolution of the 29 June supercell during STEPS
Sarah A. Tessendorf, Colorado State University, Ft. Collins and UCAR/SOARS, Boulder, CO; and S. A. Rutledge
The Severe Thunderstorm Electrification and Precipitation Study (STEPS) took place between 17 May 2000 and 20 July 2000 in eastern Colorado and western Kansas. The study aims to find a relationship between the microphysics and dynamics of severe storms on the High Plains and their unique positive cloud-to-ground lightning production. Observational platforms used in this study consisted of three S-band Doppler radars (NCAR S-Pol, CSU-CHILL, and the KGLD WSR-88D), two of which have multi-parameter capabilities, and several other platforms such as the MGLASS mobile sounding unit, the National Lightning Detection Network (NLDN), and a lightning mapping array from New Mexico Tech. On 29 June 2000, a severe thunderstorm was observed by the STEPS radar network near Bird City, Kansas. Storm characteristics included large hail, frequent positive cloud-to-ground lightning, and an F1 tornado. The storm was first detected at 2130 UTC and remained within the STEPS radar network for a significant portion of its lifetime. Multiple-Doppler wind synthesis was analyzed for the period 2130-0115 UTC to estimate the evolution of the three-dimensional wind field of this storm. Bulk hydrometeor types were objectively determined using the multi-parameter variables available on the NCAR S-Pol and CSU-CHILL radars. The Doppler-derived kinematic fields were then compared with the microphysical classifications to look for trends in the evolution of these variables. Features of interest are the relationship of vertical velocity to hail production, rain rates, and cloud-to-ground lightning polarity and frequency. Results of these correlations will be presented.

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